UPDATE: 4/2/08 Click here. The Soneils appear to be doing two stage constant voltage charging, which is specified in the B&B technical manual. So the Soneils appear to have a suitable algorithm, though I wouldn't consider it optimal.
I was looking at buying six 12v chargers for my motorcycle. I've decided that my Zivan in combination with powercheqs is not satisfactory, and will reduce the life of my batteries severely.
At first glance these 1214S Soneils are ideal: http://www.electricrider.com/chargers/specsheets/1214s.pdf
But the charging curve is different from that specified from the B&B spec sheet. The CV stage needs to be 14.4-15v until the current tapers off to about .01 CA or .35 amps (35ah batteries).
The soneil 1214s, and a few others that I reviewed (4808SRF, 1212SR, 1206S) all hold the voltage constant at 14.4v ONLY until the current drops to .5CC (or half of what the constant current mode is for that particular charger). Then they reach what's called the "switch point", and they all drop the voltage to 13.8v indefinitely in float mode. They don't stay in the CV stage long enough.
This is insufficient for cycle use of my batteries according to the spec sheet linked above. I reviewed the spec sheets of some other AGM batteries.
Cycle Applications: Limit initial current to 10A. Charge until battery
voltage (under charge) reaches 14.40 to 14.70 volts at 68oF (20oC).
Hold at 14.40 to 14.70 volts until current drops to approximately 350mA.
# Set the charge voltage to 2.37 to 2.40 V./cell (14.2 to 14.4 V. for a 12 volt battery).
# Charge the battery until the charger reaches the 2.37 to 2.40 V./cell (14.2 to 14.4 for a 12 volt battery) and leave the battery on charge for an additional 4 to 6 hours before removing it from the charger.
# Alternately, the battery can be charged to the voltage setting [2.37 to 2.4 vpc] until the current from the charger drops to 0.5 A. per 100 Ampere Hour rating of the battery.
And this is interesting from the Odyssey Technical Manual:
If the charger has a timer, then it can switch from
absorption mode to float mode when the current drops
to 0.001C10 amps. If the current fails to drop to 0.001C10
amps, then the timer will force the transition to a float
charge after no more than 8 hours. As an example, for a
PC1200 battery [44 ah 12v battery], the threshold current should be 44mA.
Another option is to let the battery stay in the absorption
phase (14.7V or 2.45 VPC) for a fixed time, such as 6-8
hours, then switch to the continuous float charge.
Because the charger in Design 3 does not have a timer,
the threshold current to trigger the switch from the
absorption phase to the temperature-compensated float
charge phase is kept relatively high [at .10 C10]. Note that in this
design the battery will not be fully charged when the
charger switches to the float charge phase. A minimum
of 16-24 hours on float will be required to complete the
From this I can conclude:
1. Some Soneil chargers may not be charging AGM batteries in accordance with their manufacturer spec for cycle use. The consequences are unknown, but this may have an impact on cell balance, by not being able to charge all of the cells to 100% in a reasonable amount of time.
2. A full charge may require the charger to be left on much longer than after the light turns green. How much longer depends, but this may be longer than 24 hours.